This invention relates to improved latching means and, more particularly, to an over-center or toggle type latch for releasably securing two adjacent parts, such as for securing a cover to a container.
Over-center or toggle action type latches, per se, are well known. Many toggle latch mechanisms, however, are difficult or impossible to open and close by hand when they are tightened to the high drawbolt loads required to seal containers such as are used to ship munitions and the like. Latch opening and closing forces in excess of one hundred pounds have been measured on some munition containers presently in use, and special tools are often required in order to apply the forces necessary to operate such latches. This is an undesirable situation inasmuch as at least one such special tool must usually be furnished with each container, and quite often the special tool is soon misplaced or lost.
A drawback to many available latches which are designed to be opened and closed by hand is the presence of large exposed surfaces which function as handles. These handles are easily damaged by blows or by the accidental hooking of the handles on adjacent objects. In U.S. Pat. No. 3,954,293 issued to W. A. Orr on May 4, 1976, there is disclosed a self-protecting latch which avoids the aforementioned objectionable feature by eliminating the large exposed handle in favor of a socket, and includes a special channel member having elongated parallel sidewalls which protect to some extent the operative elements of the latch.
A modified embodiment of the self protecting latch shown in the Orr patent, supra, has been used with some government munition containers. It includes a base member in the form of a U-shaped channel or cage having parallel sidewalls of uniform height. The cage is welded to the container at a wide opening formed in the extruded sidewall of the container. The latch mechanism, including a latch handle and its drawbar pivot elements are protected by the cage.
Various flush-mounted latch mechanisms are also known in which the mechanisms have a dished or concave base plate which is mounted by bolts or the like within an opening in the sidewall of the associated container. An example of such a latch mechanism is disclosed in U.S. Pat. No. 2,605,123 issued to A. Claud-Mantle on July 29, 1952.
While the aforementioned patents disclose latching devices which provide a measure of protection against accidental operation or damage, they all require either a special mounting channel, cage or base plate of considerable manufacturing and assembly costs, and they still must be bolted, welded or otherwise affixed to a container, a further cost in terms of both labor and material.